hichembell Posted January 15, 2019 Share Posted January 15, 2019 Hello, My DT50 is blowing the main fuse ( you can read details in my previous post..Would like to thank the community for their help) I would like to troubleshoot the power tubes. Is it safe to try to power my amp without power tubes? The idea behind this is the following: if the problem lies in tubes then the amp won't blow the fuse. Here is what I found on another forum : " You can remove all the tubes no problem. It can be very helpful in determining if a bad tube in an amp is causing a fuse to blow of something else. Remove the rectifier and power tubes. Turn on amp. Fuse blows then you have bigger issues. If it doesn't you put in the rectifier. Blows fuse? bad rectifier. No? put the power tubes in. Blows fuse? bad power tube...etc... Bob" Since there is no tube amp specialist around here, I would like to, try at least, troubleshoot the problem myself before taking it to an electronics engineer. Example, if the problem lies in power tubes I would buy them, take the amp to an electrics engineer , print the necessary documents on biasing the amp ( putting the DT on class ab/ 36 MV as a standard biasing value ..etc) , and ask him to directly change the tubes and bias the amp. Your comments are welcomed, thank you in advance. Quote Link to comment Share on other sites More sharing options...
seldon1 Posted January 15, 2019 Share Posted January 15, 2019 I don't know about turning on the amp with the valves out. I personally would not do that. New, correctly biased valves (tubes) is always a good idea in my opinion. I would start with that. Have a professional install a manufacturers recommended matched pair and a new pre-amp valve as well. I wonder if the main problem is the voltage coming out of the wall. I don't know how stable that is. I personally never plug my DT's into the wall. I have a power conditioner that not only mitigates spikes but is also a voltage regulator to guard against sags or fluctuations in voltage. I would strongly recommend a voltage regulator. Best of luck. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted January 15, 2019 Share Posted January 15, 2019 Yeah, good idea. An analog tube amp, can check without tubes in it for certain things. Probably not a good idea with these, with the digital board that has expectations from the tube section. Tubes choices to use for the DT Series,... DT-50 Series: 12AX7EH Electro-Harmonix approved for the DT50 pre-amps. EL34EH Electro-Harmonix (matched pairs) for the power amps. DT-25 Series: 12AX7B China for pre-amps. EL84EH Electro-Harmonix (matched pairs) for the power amps. Power amp tube choices are crucial, and must be properly biased by a tech or Line 6 authorized service center who knows the product. Don't do this yourself, the shock hazard is too great,... and it hurts when you get electric shock. Leave it to a tech trained who is for this. These valve amps are particular about tubes and tube brands. Do Not use substitutes, No Mesa, Groove Tube, Tung-Sol or JJ substitutes. No hot rodding of an already Bogner hot rod. Quote Link to comment Share on other sites More sharing options...
hichembell Posted January 15, 2019 Author Share Posted January 15, 2019 Changed the tubes with new ones. Like mentioned everywhere in this forum I used the same brand, the same reference : 12AX7EH Electro-Harmonix approved for the DT50 pre-amps. EL34EH Electro-Harmonix (matched pairs) for the power amps. Unfortunately, the same problem..... powered it up .... the main fuse blew .... I am very sad ...taking into consideration the fact that parts are not available in Algerie and the impossibility to send it to line6 for repair.....it was my dream amp for a couple of months... the possibility of repairing the repairing the inboard power transformer sounds impossible apparently Quote Link to comment Share on other sites More sharing options...
psarkissian Posted January 16, 2019 Share Posted January 16, 2019 Have you opened the chassis yet? If not, don't do anything yet. I'll be back in the morning here. Quote Link to comment Share on other sites More sharing options...
hichembell Posted January 16, 2019 Author Share Posted January 16, 2019 Didn't open the chassis of course...wouldn't do that without a qualified technician or electronics engineer with me. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted January 16, 2019 Share Posted January 16, 2019 Okay. Good. Quote Link to comment Share on other sites More sharing options...
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